Rag guard for positive displacement pumps



July 16, 1963 M. NEcHlNE RAG GUARD FOR POSITIVE DISPLACEMENT PUMPS Filed Oct. 25, 1959v Q nm ,u ZZ

United VStates Patent O 3,097,609 RAG GUARD FOR POSITISVE DISPLACEMENT PUMP Leonard M. Nechine, Highland Park, Ill., assignor t FMC Corporation, a corporation of Delaware Filed Oct. 23, 1959, Ser. No. 848,447 6 Claims. (Cl. 103-117) This invention relates to a rag guard for positive displacement pumps particularly adapted to prevent rags and stringy material entering the suction chamber from being wrapped around the rotating drive shaft.

The present invention will be described with reference to a pump suitable for sludge pumping in which a rotating drive shaft is connected to one end of a rotor by a universal joint located in the suction chamber of the pump. In pumps of this type rags and stringy material entering the suction chamber have a tendency to be wrapped around the exposed portion of the drive shaft or the universal joint so as to impair the efliciency of the pump.

TheV rag guard comprises a exible member, preferably rubber, in the shape of a truncated cone having one end held between the flanges of the suction chamber and the packing box flange. The smaller end of the rag guard bears on .a smooth surface of the rotor adjacent the universal joint. The rag guard is apertured to equalize the pressure on both sides so that it will not be forced out of position by pressure differential. The rag guard is molded with an expansion fold adjacent its large end so that the circular motion of the rotor will not cause displacement of the small end of the rag guard.

The stationary surface of therag guard causes rags and stringy material entering the suction chamber to ow directly into 4the opening of thepumping area between rotor and stator so that they are carried to the discharge end of the pump without interfering vwith the operation of the pump.

The structure by means of which the above-mentioned and other advantages of the invention are attained will be fully described in the following specification, taken in conjunction with the accompanying drawings showing a preferred illustrative embodiment of the invention, in which:

FIG. l is a fragmentary longitudinal sectional view of a pump provided with a rag guard embodying the invention;

FIG. 2 is an enlarged fragmentary longitudinal sectional view of the rag guard; and

FIG. 3 is a cross sectional view, taken along the line 33 of FIG. 2.

As shown in FIG. 1, the pump comprises a centrally disposed suction chamber 2 connected at one end to a housing 3 in which a drive shaft 4 is mounted, and at its other end to a housing 5 leading to a discharge outlet 6. Standards 7 -of any suitable construction support the pump in horizontal position. Housing 3 includes a packing box 8 having an annular flange 9 secured to flange 1l)` of suction chamber 2 by bolts 11. A sleeve 12 rotatably mounted in one end of housing 3 is provid-ed with end thrust bearings 13- near its outer end and bearings 14 near its inner end.

The opposite ends 15 and 16 of drive shaft 4 are tapered. A com-pressible gasket 17 provides a seal between end 15 vof drive shaft 4 and the inner surface of sleeve 12. End 15 is provided with a transverse opening 18 the sides of which taper outwardly slightly from the center. A pin 19 extends through opening 18 and aligned openings 20 in sleeve 12. The ends of pin 19 are threaded into openings 21 in a ring 22 to provide a universal joint for holding end 15 of drive shaft 4 so that it is rotated and oscillated by the rotation of sleeve 12 which is operatively connected to one end of the drive shaft of a motor (not shown).

End 16 of drive shaft 4 iits into a recess 23 in one end of a rotor 24. A compressible gasket 25 provides a seal between end 16 of drive shaft 4 and recess 23. End -16 is also provided with a transverse opening 26 tapered in the same manner as opening 18. A pin 27 extending through opening 26 and aligned openings 28 in the end of rotor 24 is -secured in place by a ring 29 extending around .the outer periphery of the adjacent end portion of rotor 24 and rigidly secured thereto in any suitable manner.

A stator 30 in housing 5 is provided with undulating surfaces l31, and rotor 24 is shaped in complementary manner to surfaces 31. As the rotor is rotated and moved with the circulatory movement imparted thereto by the rotation and oscillation of drive shaft 4, spaces 32, between the outer surface of the rotor and the inner surface of stator 301, are progressively moved outwardly from suction chamber 2 to discharge outlet 6. The rotor acts as la screw to move the material entering the suction chamber through an inlet 33 through housing 5 toward discharge outlet v6. Sludge is moved through the pump without difficulty, but rags and stringy material have a tendency to become wrapped aro-und the drive shaft and thereby impair the efliciency of the pump.

A rag guard 34 of any sui-table iiexible material, preferably rubber, is secured at one end by an annular ange 35 clamped between anges 9 and 10. The opposite end 36 of .the rag guard, Whichgis of increased thickness, is positioned on the outer surface of ring 29. The circulatory motion of ring 29jwith the adjacent end of rotor 24 has a tendency .to distort the rag guard trans-v passage of rags or stringy material therethrough, and

such material is carried by the iniiowing liquid directly to the opening of the pumping area between rotor 24 and stator 30.

Although I have described a preferred embodiment of the invention in considerable detail it will be understood .that the description thereof is intended to be illustrative, rather than restrictive, as many details of construction may be modified or changed without departing from the spirit or scope of the invention. Accordingly, I do not desire to be restricted to the exact structure disclosed.

I claim:

l. In combination with a pump having a housing forming a suc-tion chamber, a drive sh-aft having one end positioned in said suction chamber, and a rotor having one end secured to said 'one end of said drive shaft, la flexible tubular rag guard enclosing the connection between said rotor and said drive shaft, said rag guard having apertures providing passageways for liquid from said suction chamber to the space enclosed by said rag guard -to equalize the pressure within said rag guard and said suction chamber, said apertures being too small to admit rags into the space enclosed by said rag guard, one end of said rag guard slidably engaging the connection between said rotor and lsaid drive shaft, and the other end of said rag guard being fixed relative to said housing.

2. A pump comprising a housing forming a suction chamber, a rotor having one end extending into said suction chamber, -a drive shaft having one end connected to Patented July 16, 1963- said one end of the rotor, and a Iflexible tubular rag guard enclosing the connection between said drive shaft and rotor, said rra-g guard having one end tired relative to said housing, the other end of said rag guard moving in a circular path with said rotor and said one end of the drive shaft, said one end of the rotor and said one end of the drive shaft rotating within a portion of said rag guard adjacent the last mentioned end of said rag guard, said rag guard having a plurality of apertures too small to permit rags to pass therethrough, said apertures providing passageways for liquid 4from said suction chamber to equalize the pressure within the space enclosed by said rag guard and the rest of the suction chamber.

'3. A pump comprising -a housing Iforming a suction chamber, a rotor having one end extending into said sucytion chamber, a drive shaft having one end connected to said one end of the rotor, and ,a flexible tubular rag guard enclosing -the connection between said drive shaft and rotor, said rag guard having one end fixed relative to said housing, the other end of said rag guard moving in a circular path with said rotor and said one end of the `drive shaft, said one end of the rotor and said one end of the drive shaft rotating within .a portion of said rag guard adjacent the last mentioned end of said rag guard, said rag guard having an annular fold adjacent said rst mentioned end to prevent displacement of said rag guard relative to said rotor as said last mentioned end moves in said circular path with said rotor and drive sha-ft.

4. A pump comprising a housing forming a suction chamber, a rotor having one end extending into said suction chamber, a drive shaft having one end connected to said one end of the rotor, 'and a flexible tubular rag guard enclosing the connection between said drive shaft and rotor, said rag guard having one end fixed relative to said housing, the other end of said rag guard moving in a circular path with said rotor and said one end of the drive shaft, said one end of the rotor and said one end of the drive shaft rotating Within a portion of said rag guard adjacent the last mentioned end of said rag guard, said rag guard having a plurality of apertures too small to permit rags -to pass therethrough, said Iapertures providing passageways for liquid from said suction chamber to equalize the pressure Within the space enclosed by said rag guard and the rest of the suction chamber, said rag guard having an annular fold adjacent said first mentioned end to prevent displacement of said rag guard relative to said rotor as said last mentioned end moves in Asaid circular path with said -rotor and drive shaft.

5. A pump comprising a housing forming a suction chamber, a rotor having one end positioned in said suction chamber, said one end having an axial recess therein, a drive shaft having one end secured in said recess, and a exible tubular rag guard having 'one end fixed relative to said housing, the other end of said rag guard fitting around said one end of said rotor whereby said rag guard encloses the portion of said drive shaft in said suction chamber and the `connection between said drive shaft and rotor, said rag guard having an annular fold adjacent the rst mentioned end thereof to prevent displacement from said rotor, said rotor being rotatable relative to said last mentioned end of said rag guard, -and said rotor `being movable in a circular path with said one end of the drive shaft and said last mentioned end of said rag guard.

6. A pump `comprising -a housing forming a suction chamber, a rotor having one end positioned in said suction chamber, said one end having an axial recess therein, a drive shaft having end end Isecured in said recess, and a flexible tubular rag guard having one end fixed relative to said housing, the other end of said rag guard tting around said one end of said rotor whereby said rag guard encloses the portion of said drive shaft in said suction chamber `and the connection between said drive shaft and rotor, said rag guard having an annular fold adjacent the first mentioned end thereof to prevent displacement from said rotor, said rotor being movable in a circular path with said one end of the drive shaft and said last mentioned end of said rag guard, said rag guard having a plurality of ,apertures too small to permit rags to pass therethrough, ysaid apertures providing passageways for liquid from said suction chamber to equalize the pressure within the space enclosed by said rag guard -and the rest of the suction chamber.

References Cited in the le of this patent UNITED STATES PATENTS 1,807,139 Volodimirov May 26, 1931 2,107,090 Swennes Feb. 1, 1938 2,211,817 Hutferd, et al. Aug. 20, 1940 2,432,803 Rice Dec. 16, 1947 2,636,444 Salgues Apr. 28, 1953 2,695,694 Seinfeld Nov. 30, 1954 2,915,797 Bourke et al. Dec. 8, 1959 2,966,118 McAlvey Dec. 27, 1960 FOREIGN PATENTS 305,514 Switzerland Feb. 28, 1955 

1. IN COMBINATION WITH A PUMP HAVING A HOUSING FORMING A SUCTION CHAMBER, A DRIVE SHAFT HAVING ONE END POSITIONED IN SAID SUCTION CHAMBER, AND A ROTOR HAVING ONE END SECURED TO SAID ONE END OF SAID DRIVE SHAFT, A FLEXIBLE TUBULAR RAG GUARD ENCLOSING THE CONNECTION BETWEEN SAID ROTOR AND SAID DRIVE SHAFT, SAID RAG GUARD HAVING APERTURES PROVIDING PASSAGEWAYS FOR LIQUID FROM SAID SUCTION CHAMBER TO THE SPACE ENCLOSED BY SAID RAG GUARD TO EQUALIZE THE PRESSURE WITHIN SAID RAG GUARD AND SAID SUCTION CHAMBER, SAID APERTURES BEING TOO SMALL TO ADMIT RAGS INTO THE SPACE ENCLOSED BY SAID RAG GUARD, ONE END OF SAID RAG GUARD SLIDABLY ENGAGING THE CONNECTION BETWEEN SAID ROTOR AND SAID DRIVE SHAFT, AND THE OTHER END OF SAID RAG GUARD BEING FIXED RELATIVE TO SAID HOUSING. 